'Stability: 5' is described as 'Locked' not as 'API Locked'
in other documents.
For example:
- `/doc/api/assert.markdown`
- `/doc/api/util.markdown`
This word was injected in 192192a.
Noted in @shtylman's #3898, API stability notes are easy to overlook
in the html documentation. This can be especially troublesome if the API
is deprecated. This commit gives visual feedback by adding in a class
to the html docs when they're generated. The API headers with
corresponding colors are also listed in the 'About this Documentation'
page for easy reference.
Ben Noordhuis
Ryunosuke SATO
Luke Arduini
isaacs